Microbiology

Desperately Seeking Salmonella

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Science  29 Aug 2003:
Vol. 301, Issue 5637, pp. 1159
DOI: 10.1126/science.301.5637.1159d

Salmonella bacteria infect humans via contaminated food. They invade cells lining the gut wall and cause horrible dysenteric symptoms. Typhoid fever may occur when S. enterica serovar typhi escapes the gut to establish itself systemically.

Until now, research has focused on host genes or on bacterial growth in tissue culture, but little is known about how Salmonella behaves within a natural host. Sheppard et al. looked at the distribution of bacteria within the livers of systemically infected mice and found salmonellae lodged in phagocytes. The invaders multiplied clonally in discrete focal lesions, growing at independent rates and forming new foci through the dissemination of bacteria into uninfected cells. Thus, unlike cell culture assays, there was no direct correlation between infection load and bacterial number per infected cell; rather, heavier infection signified more foci, highlighting the limitations of relying on cell culture to model pathogen infection. — CA

Cell. Microbiol. 5, 593 (2003).

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